1. Field of the Invention
The present invention generally relates to container closures and, more particularly, to container closures having venting capability.
2. Description of the Related Art
Products such as hypochlorite bleach often generate gases. A major problem arises when containers containing such products are packaged, transported, and stored on store shelves. As the product evolves gases, the internal pressure of the container increases excessively and leads to various types of container failures such as bottle bulging and stress cracking. Certain other chemical products, however, may cause containers to collapse by reacting with air in the headspace and thereby reducing the internal pressure. Elevation changes during the transportation of the bottled products can also lead to an increase or decrease in the internal pressure of the containers relative to ambient pressure and cause similar effects.
One prior art way of avoiding such bottle failures has been the use of vented closures so that bulging or collapse of the containers can be precluded. In such applications, the container caps are provided with gas permeable seals or liners to permit excessive internal pressure to vent out to the atmosphere, while retaining the associated liquid within the container. As such, the release of excessive pressure is intended to prevent the aforementioned failure problems.
However, it is customary and economical during storage and transportation for the lower cases of bottles to share the load with the corrugated case in supporting the weight of cases stacked above the lower ones. Such stacks are supported, in part, by virtue of the internal pressure of the containers located in the lower level cases. A case of bottles with vented closures, however, is very ineffective in supporting additional weight because they cannot establish internal pressure and, thus, there is more cost due to the need for sturdier boxes, compared to bottles that are gas-sealed. This is because under load a sealed bottle builds up significant internal pressure (e.g., about 4-5 psig) and it is this pressure that enables the bottle to support a much greater top-load. In such a scenario, the bottle is prevented from bulging at the bottom by virtue of being compressed between two surfaces, namely, the cases above and the cases beneath. When the load is removed the bottle pressure returns to what it was before being loaded. Thus, a gas-sealed bottle is highly desirable for case stacking-strength whereas a gas-vented bottle is highly desirable when not loaded, as on a store shelf.
In view of the foregoing, there is a need for alternative container closure systems that allow venting of the containers while allowing load sharing by precluding venting when the container cases are stacked.
The present invention provides a bottle closure that seals a bottle, which contains a gas evolving liquid such as hypochlorite bleach, when a top load is applied on the closure but vents the container when the top load is absent.
Specifically, the closure of the present invention utilizes the weight of filled cases that are located at the upper levels of a case stack to seal the bottles in the cases located at the lower levels of the stack. When a load of top level cases is directed down on the bottles having the inventive closure, the closure prevents gas from escaping from the bottle through the closure and builds up internal pressure that enables the bottle to support the top load without having any container failure. In conjunction with the internal pressure created by the closure, this configuration prevents containers from bulging at the bottom by virtue of compressing each case between its upper and lower surfaces.
In one aspect of the present invention, a vented closure for preventing deformation of a container containing a gas evolving liquid comprises a first closure member and a second closure member. The first closure member seals the container from the outside atmosphere and defines a gas inlet, a gas outlet, and a gas flow passage between the inlet and the outlet. A gas permeable membrane covers the gas flow passage. The second closure member is moveably fitted on the first closure member and encases the first closure member with a small clearance fit that allows gas passage. A sealing element is coupled to the second closure member and is aligned with the gas outlet of the first member so as to block gas flow when a predetermined load is applied to the second closure member and allows the flow of gas when the predetermined load is removed.
In another aspect of the present invention, a method of transporting containers having a gas evolving liquid comprises placing a vented closure on at least one of the containers, the vented closure being in a reference position or a sealing position relative to the at least one container wherein the reference position allows gas venting from the at least one container and the sealing position prevents gas venting from the at least one container. The containers are positioned in a stacked relationship, and a load is produced on the vented closure to place the vented closure in the sealing position.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.